Process and apparatus for making composite structures

Abstract

A process and an apparatus for densifying a porous structure is disclosed. The porous structure comprises a first surface, a second surface, an inner diameter surface and an outer diameter surface. The process may comprise progressive densification in conjunction with thermal gradient and/or pressure gradient densification processes.

The invention claimed is: 
     
       1. A process comprising:
 coupling a first porous structure having a first surface and a second surface with a second porous structure having a first surface and a second surface, so that the second surface of the first porous structure is in direct contact with the first surface of the second porous structure, wherein the coupling comprises securing the first porous structure to the second porous structure with a first graphite clamp, wherein a portion of the second surface of the second porous structure is in contact with a graphite seal ring, the graphite seal ring disposed between the second surface of the second porous structure and a cooling element in thermal contact with the second surface of the second porous structure; 
 establishing a thermal gradient using a heating element in a process furnace, the temperature of the first surface of the first porous structure being higher than the temperature of the second surface of the second porous structure; 
 flowing gas through the second surface of the second porous structure, to form a solid residue within the first porous structure and the second porous structure; 
 decoupling the first porous structure and the second porous structure; 
 coupling the second porous structure with a third porous structure having a first surface and a second surface, so that the second surface of the second porous structure is in direct contact with the first surface of the third porous structure, and so that the second porous structure is coupled to the third porous structure, wherein the coupling comprises securing the second porous structure to the third porous structure with a second graphite clamp; and 
 flowing gas through the second surface of the third porous structure, while the second porous structure is coupled to the third porous structure, to form a solid residue within the second porous structure and the third porous structure. 
 
     
     
       2. The process of  claim 1 , wherein the porous structure comprises an annular structure. 
     
     
       3. The process of  claim 1 , wherein the porous structure comprises at least one of carbon, silicon carbide, silicon nitride, boron carbide, aluminum nitride, titanium nitride, boron nitride, zirconia, SiC x N y  (wherein x is a number in the range from about zero to about 1, and y is a number in the range from about zero to about 4/3), silica, alumina, titania, and a combination of at least two of the foregoing. 
     
     
       4. The process of  claim 1 , wherein the porous structure comprises a carbonized preform. 
     
     
       5. The process of  claim 1 , wherein the gas comprises a hydrocarbon of 1 to about 8 carbon atoms. 
     
     
       6. The process of  claim 1 , wherein the gas comprises a precursor that thermally reacts to form at least one of carbon, silicon carbide, silicon nitride, boron carbide, aluminum nitride, titanium nitride, boron nitride, zirconia, SiC x N y  (wherein x is a number in the range from about zero to about 1, and y is a number in the range from about zero to about 4/3), silica, alumina, titania, and a combination of at least two of the foregoing. 
     
     
       7. A process comprising:
 coupling a first porous structure having a first surface and a second surface with a second porous structure having a first surface and a second surface, so that the second surface of the first porous structure is in direct contact with the first surface of the second porous structure, wherein the coupling comprises securing the first porous structure to the second porous structure with a first graphite clamp, wherein a portion of the second surface of the second porous structure is in contact with a graphite seal ring, the graphite seal ring disposed between the second surface of the second porous structure and a cooling element in thermal contact with the second surface of the second porous structure; 
 establishing a thermal gradient using a heating element in a process furnace, the temperature of the first surface of the first porous structure being higher than the temperature of the second surface of the second porous structure; 
 flowing gas through the first surface of the first porous structure, to form a solid residue within the first porous structure and the second porous structure; 
 decoupling the first porous structure and the second porous structure; 
 coupling the second porous structure with a third porous structure having a first surface and a second surface, so that the second surface of the second porous structure is in direct contact with the first surface of the third porous structure, and so that the second porous structure is coupled to the third porous structure, wherein the coupling comprises securing the second porous structure to the third porous structure with a second graphite clamp; and 
 flowing gas through the first surface of the second porous structure, while the second porous structure is coupled to the third porous structure, to form a solid residue within the second porous structure and the third porous structure. 
 
     
     
       8. The process of  claim 7 , wherein the porous structure comprises an annular structure. 
     
     
       9. The process of  claim 7 , wherein the porous structure comprises at least one of carbon, silicon carbide, silicon nitride, boron carbide, aluminum nitride, titanium nitride, boron nitride, zirconia, SiC x N y  (wherein x is a number in the range from about zero to about 1, and y is a number in the range from about zero to about 4/3), silica, alumina, titania, and a combination of at least two of the foregoing. 
     
     
       10. The process of  claim 7 , wherein the porous structure comprises a carbonized preform. 
     
     
       11. The process of  claim 7 , wherein the gas comprises a hydrocarbon of 1 to about 8 carbon atoms. 
     
     
       12. The process of  claim 7 , wherein the gas comprises a precursor that thermally reacts to form at least one of carbon, silicon carbide, silicon nitride, boron carbide, aluminum nitride, titanium nitride, boron nitride, zirconia, SiC x N y  (wherein x is a number in the range from about zero to about 1, and y is a number in the range from about zero to about 4/3), silica, alumina, titania, and a combination of at least two of the foregoing. 
     
     
       13. A process comprising:
 establishing a thermal gradient using a heating element in a process furnace containing a porous structure having a first surface and a second surface, the temperature of the first surface of the porous structure being higher than the temperature of the second surface of the porous structure, wherein a portion of the second surface of the porous structure is in contact with a graphite seal ring, the graphite seal ring disposed between the second surface of the second porous structure and a cooling element in thermal contact with the second surface of the second porous structure; 
 flowing gas through the second surface of the porous structure to form a solid residue within the porous structure; 
 cutting the porous structure to form a first porous structure remnant and a second porous structure remnant, the first porous structure remnant having a thickness less than the porous structure; 
 coupling the second porous structure remnant with a second porous structure having a first surface and a second surface, so that the second surface of the second porous structure remnant is in direct contact with the first surface of the second porous structure, and so that the second porous structure remnant is coupled to the second porous structure, wherein the coupling comprises securing the second porous structure remnant to the second porous structure with a graphite clamp; and 
 flowing gas through the second surface of the second porous structure, while the second porous structure remnant is coupled to the second porous structure, forming a solid residue within the second porous structure remnant and the second porous structure. 
 
     
     
       14. The process of  claim 13 , wherein the porous structure comprises an annular structure. 
     
     
       15. The process of  claim 13 , wherein the porous structure comprises at least one of carbon, silicon carbide, silicon nitride, boron carbide, aluminum nitride, titanium nitride, boron nitride, zirconia, SiC x N y  (wherein x is a number in the range from about zero to about 1, and y is a number in the range from about zero to about 4/3), silica, alumina, titania, and a combination of at least two of the foregoing. 
     
     
       16. The process of  claim 13 , wherein the porous structure comprises a carbonized preform. 
     
     
       17. The process of  claim 13 , wherein the gas comprises a hydrocarbon of 1 to about 8 carbon atoms. 
     
     
       18. The process of  claim 13 , wherein the gas comprises a precursor that thermally reacts to form at least one of carbon, silicon carbide, silicon nitride, boron carbide, aluminum nitride, titanium nitride, boron nitride, zirconia, SiC x N y  (wherein x is a number in the range from about zero to about 1, and y is a number in the range from about zero to about 4/3), silica, alumina, titania, and a combination of at least two of the foregoing. 
     
     
       19. A process comprising:
 coupling a first porous structure system having a first surface and a second surface with a second porous structure system having a first surface and a second surface, so that the second surface of the first porous structure system is in substantial contact with the first surface of the second porous structure system, wherein the coupling comprises securing the first porous structure system to the second porous structure system with a first graphite clamp, wherein a portion of the second surface of the second porous structure system is in contact with a graphite seal ring, the graphite seal ring disposed between the second surface of the second porous structure and a cooling element in thermal contact with the second surface of the second porous structure; 
 establishing a thermal gradient using a heating element in a process furnace, the temperature of the first surface of the first porous structure system being higher than the temperature of the second surface of the second porous structure system; 
 flowing gas through the second surface of the second porous structure system, to form a solid residue within the first porous structure system and the second porous structure system; 
 separating at least one of the first porous structure system and the second porous structure system to yield a first porous subsystem; 
 coupling the first porous subsystem with a third porous structure system having a first surface and a second surface, so that the second surface of the first porous subsystem is in substantial contact with the first surface of the third porous structure system, and so that the first porous subsystem is coupled to the third porous structure system, wherein the coupling comprises securing the first porous subsystem to the third porous structure system with a second graphite clamp; and 
 flowing gas through the second surface of the third porous structure, while the first porous subsystem is coupled to the third porous structure system, to form a solid residue within the first porous subsystem and the third porous structure system. 
 
     
     
       20. The process of  claim 19 , wherein the second porous structure system comprises at least two porous structures.